DRM (acronym of Digital Rights Menagement) it’s a form of protection of multimedia digital contets such as audio and video for copyright.
How many times you encountered to being able to reproduce an audio or video file in your computer? There are various programs to let bypass these protections, most known are Fairuse4WM, Freeme2. Recently a new entry, the Hymn project released under GPL license that will allow to decrypt iTunes protected tracks (AAC).
However for a full list of these software you can refer to this forum.
Moreover that forum is rich of many info and resources about audio and video streaming and recordig, surely to read!